To create a Parent Account within the Charts of Accounts, click on the Create New button on the upper left side of the screen.
At the Add Account window, type a name for the Account Name, select the Account Type, leave the the Parent Account as "No Parent Account", then click Save & Close.
After saving the newly created Parent Account, it can now be used when creating sub-entries. Click on the Create New button on the upper left side of the screen again to open the Add Account window.
The Parent Account and the sub-account created will appear within the Chart of Accounts similar to the image below.